1. Field of the Invention
The present invention relates to a semiconductor light emitting element having a transparent conductive oxide film as an electrode.
2. Background Information
Semiconductor light emitting elements having a p-type semiconductor layer and an n-type semiconductor layer laminated onto a substrate, and electrodes that are electrically connected to the respective p-type and n-type semiconductor layers, are well known in the prior art. In addition, as the electrode that is electrically connected to the p-type semiconductor layer, a structure in which an electrode made of a transparent material is formed on the entire surface of the p-type semiconductor layer and a metal electrode is formed thereon, is well known.
With semiconductor light emitting elements having this type of structure, in order to improve light extraction efficiency, a transparent metal thin film, or a conductive oxide film of ITO, ZnO, In2O3 or the like, is employed as the electrode formed on the entire surface of the p-type semiconductor layer (see, for example, JP-A-2001-196633).
However, because a conductive oxide film, e.g., ITO, exhibits n-type semiconductor characteristics, the ohmic characteristics with the semiconductor layer will not necessarily be good, and because of various factors such as the composition of semiconductor layer, the conductive type, the film formation method, and the like, a Schottky barrier will be formed, and contact resistance will increase. Thus, there will be problems such as restrictions on the conditions under which the semiconductor layer and the conductive oxide film are formed, and the impurity concentration, the conductive type, and the like, or a decline in electrical energy conversion efficiency or light extraction efficiency due to a worsening of the ohmic characteristics toward the semiconductor layer of the conductive oxide film.
The present invention takes the aforementioned problems into consideration, and aims to provide a semiconductor light emitting element having a transparent conductive oxide film on a semiconductor layer, and which is comprised of an electrode that can maintain sufficient transparency and improve light emission efficiency while reducing the Schottky barrier between the semiconductor layer and the conductive oxide film, reduce contact resistance to a minimum, and achieve an excellent ohmic contact.